1. Field of the Invention
An air conditioner, and more particularly, an air conditioner that is capable of continuously performing a heating operation without requiring a defrosting operation.
2. Description of the Related Art
Generally, an air conditioner is an apparatus for cooling or heating an indoor space, using a refrigeration cycle including a compressor, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger. The air conditioner may include a cooler for cooling an indoor space and a heater for heating an indoor space. Alternatively, the air conditioner may be a cooling and heating air conditioner for cooling or heating an indoor space.
The cooling and heating type air conditioner may include a 4-way valve for changing a flow path of a refrigerant compressed by a compressor in accordance with cooling and heating operations. That is, in the cooling mode, the refrigerant compressed by the compressor is delivered to an outdoor heat exchanger after passing through the 4-way valve. In this case, the outdoor heat exchanger operates as a condenser. The refrigerant, which is condensed in the outdoor heat exchanger, is introduced into an indoor heat exchanger after being expanded by an expansion device. In this case, the indoor heat exchanger operates as an evaporator. The refrigerant, which is evaporated in the indoor heat exchanger, is introduced into the compressor after again passing through the 4-way valve.
Meanwhile, in a heating mode, the refrigerant compressed by the compressor is delivered to the indoor heat exchanger after passing through the 4-way valve. In this case, the indoor heat exchanger operates as a condenser. The refrigerant, which is condensed in the indoor heat exchanger, is introduced into the outdoor heat exchanger after being expanded by the expansion device. In this case, the outdoor heat exchanger operates as an evaporator. The refrigerant, which is evaporated in the outdoor heat exchanger, is introduced into the compressor after again passing through the 4-way valve.
In such an air conditioner, water is produced on the surface of the heat exchanger operating as an evaporator during operation of the air conditioner. That is, water is produced on the surface of the indoor heat exchanger in the cooling mode, whereas water is produced on the surface of the outdoor heat exchanger in the heating mode. When water produced on the surface of the outdoor heat exchanger in the heating mode is frozen, smooth flow and efficient heat exchange of outdoor air may not be achieved. As a result, heating performance may be degraded.
Accordingly, when the refrigeration cycle operates in a reverse cycle mode (e.g., cooling operation) during heating operation in order to remove frozen condensed water, high-temperature and high-pressure refrigerant passes through the outdoor heat exchanger and, as such, frozen water on the surface of the outdoor heat exchanger is thawed by heat of the refrigerant. However, when the defrosting operation is performed using the reverse refrigeration cycle, there may be a problem because the indoor space heating should be stopped.
To solve the above-mentioned problem, Korean Unexamined Patent Publication No. 10-2009-0000925 discloses an air conditioner in which an outdoor heat exchanger is divided into a plurality of heat exchanger sections such that one of the heat exchanger sections performs heating operation, to operate as an evaporator, and the other of the heat exchanger sections performs defrosting operation by receiving high-pressure refrigerant from a compressor. However, because refrigerant used to defrost one heat exchanger section is introduced into an outlet stage of the other heat exchanger section, the temperature and pressure of the heat exchanger section performing heating operation (evaporator) are increased. As a result, insufficient heat exchange may be carried out in the heat exchanger section performing heating operation and, as such, there may be a problem in that the efficiency of the air conditioner may be degraded.
In the case in which a plurality of heat exchanger sections are used, there may be a problem in that the efficiency of the heat exchanger may be degraded when defrosting operation is carried out after formation of frost.